1. Field of the Invention
The present invention relates to a transflective liquid crystal display device, particularly to a transflective liquid crystal display device for preventing interferences caused by reflecting light in a reflective mode and for improving contrast in a transmissive mode.
2. Description of Related Art
A so-called transflective liquid crystal display device, which reflects external light incident from the front side, guides it to the front side and at the same time allows incident light from a backlight system on the back to pass and guides it to the same front side, is entering into a full-fledged commercial stage. This type of liquid crystal display device provides effective image displays using principally external light (ambient light) when an environment in which it is used is bright (reflective mode) and principally self-emitted light from the backlight system when the environment is dark (transmissive mode).
A prior art document “Development of Advanced TFT with Good Legibility under Any Intensity of Ambient Light” (by M. Kubo, et al., IDW' 99, Proceedings of The Sixth International Display Workshops, AMD3-4, page 183-186, Dec. 1, 1999, sponsored by ITE and SID) discloses such a liquid crystal display device.
A reflective liquid crystal display device uses a diffusive reflective plate to efficiently transform incident light into reflecting light. This diffusive reflective plate normally has an uneven surface, capable of regularly reflecting incident light as well as adding the diffused/reflected component on this uneven surface to the reflecting light. Since the transflective liquid crystal display device includes a reflection area in pixels, it also uses a diffusive reflective plate.
In a transflective liquid crystal display device having a diffusive reflective plate, when incident light is reflected on the uneven surface of the diffusive reflective plate, different light rays in the same optical path direction are produced on one convex part of the uneven surface; light rays near the vertex of the convex part and light rays near the valley of the convex part, which interfere with one another causing a phenomenon of iridescence.
For this reason, in order to cause the light rays in the same optical path direction to have different optical path directions, the transflective liquid crystal display device having a diffusive reflective plate uses a polarizer subjected to anti-glare treatment or an adhesive glue (diffusive adhesive glue) having a diffusive characteristic.
However, the above described transflective liquid crystal display device has a problem that due to the polarizer subjected to anti-glare treatment or the adhesive glue having a diffusive characteristic, and a diffusive adhesive glue in particular, transmissive light is diffused in a transmissive mode and contrast in the transmissive mode is thereby reduced.
The present invention has been implemented in view of the above described problem and it is an object of the present invention to provide a transflective liquid crystal display device capable of preventing interferences caused by reflecting light in the reflective mode and improving contrast in the transmissive mode.